假如有這樣一組數據

var oldData=[
   {date:'2019-08-26',"queue_id":219,"queue_num":4,"queue_status":1,"queue_name":'預約接種'},
   {date:'2019-08-26',"queue_id":218,"queue_num":2,"queue_status":1,"queue_name":'預約接種'},
   {date:'2019-08-25',"queue_id":217,"queue_num":1,"queue_status":1,"queue_name":'預約接種'}
]      

我想把擁有相同日期的數據，放在一個數組里面，

第一種方案

1、首先我們把源數據先變成目標數據的規則

var oldDataRule = []
oldData.forEach(el => {
  var oldObj = {
    date: el.date,
    list:[]
  }
  oldObj.list.push(el)
  oldDataRule.push(oldObj)
})
console.log(oldDataRule)

打印出來的數據如下

20190830141919.png

            var newData = []
            var newObj = {}
            oldDataRule.forEach((el, i) => {
              if (!newObj[el.date]) {
                newData.push(el);
                newObj[el.date] = true;
              } else {
                newData.forEach(el => {
                  if (el.date === oldDataRule[i].date) {
                    el.list = el.list.concat(oldDataRule[i].list);
                    // el.list = [...el.list, ...oldDataRule[i].list]; // es6語法
                  }
                })
              }
            })
            console.log(newData)

最后出來的結構如下

QQ截圖20190830150433.png

第二種方案

var oldDataRule = []
var newData = []
oldData.forEach( item =>{
  oldDataRule [item.date] = oldDataRule [item.date] || [];
  oldDataRule [item.date].push(item);
})
for (let key in oldDataRule ) {
  let obj = {}
  obj.date = key
  obj.list =arr[key]
  newData.push(obj)
}